Coated articles are known in the art for use in window applications such as insulating glass (IG) window units, vehicle windows, and/or the like. It is known that in certain instances, it is desirable to heat treat (e.g., thermally temper, heat bend and/or heat strengthen) such coated articles for purposes of tempering, bending, or the like in certain example instances.
In certain situations, designers of coated articles often strive for a combination of desirable visible transmission, desirable color(s) at both normal and off-axis viewing angles, low emissivity (or emittance), and low sheet resistance (Rs). High visible transmission for example may permit coated articles to be more desirable in certain window applications, whereas low-emissivity (low-E) and low sheet resistance characteristics permit such coated articles to block significant amounts of IR radiation so as to reduce for example undesirable heating of vehicle or building interiors. However, heat treatment of coated articles typically requires use of temperature(s) of at least 580 degrees C., more preferably of at least about 600 degrees C. and still more preferably of at least 620 degrees C. The use of such high temperatures (e.g., for 5-10 minutes or more) often causes coatings to break down, have undesirable off-axis color values, and/or causes one or more of the aforesaid desirable characteristics to significantly deteriorate in an undesirable manner.
U.S. Patent Document 2005/0202254, commonly owned and hereby incorporated herein by reference, discloses a coated article having the following layers on a glass substrate, from the glass substrate outwardly.
Layer
Glass Substrate
TiO2 
Si3N4 
ZnO
Ag
NiCrOx 
SnO2 
Si3N4 
SnO2 
ZnO
Ag
NiCrOx 
SnO2 
Si3N4 
While the aforesaid coated article is heat treatable, and has many desirable and good characteristics, it does have problems with reddish off-axis coloration at high off-axis viewing angles. For example, the Comparative Example of this discussed in Ser. No. 11/522,512 filed Sep. 18, 2006 (hereby incorporated herein by reference) had a reflective glass side coloration Rga* (45°) value of +5 which is very reddish at this off-axis viewing angle.
U.S. Patent Document 2005/0196622 discloses a coated article including a layer stack of silicon nitride, NiCr, silicon nitride, etc. in a bottom portion of the coating. However, 2005/0196622 does not disclose or suggest that the NiCr layer has any bearing on off-axis coloration. Moreover, it has been found that locating the NiCr absorbing layer below both IR reflecting layers is not desirable for certain off-axis coloration values desired herein.
In view of the above, it will be apparent to those skilled in the art that there exists a need in the art for a coated article with more desirable (e.g., less red and/or more green) off axis coloration.